(PECL imagick 2.2.1)
Imagick::getImageChannelRange — Gets channel range
Gets the range for one or more image channels. This method is available if Imagick has been compiled against ImageMagick version 6.4.0 or newer.
Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channel constants using bitwise operators. Defaults to Imagick::CHANNEL_DEFAULT. Refer to this list of channel constants
Returns an array containing minima and maxima values of the channel(s).
Throws ImagickException on error.